Animals including mammals and birds are often susceptible to parasite infestations/infections. These parasites may be ectoparasites or endoparasites. Domesticated animals, such as cats and dogs, are often infested with one or more of the following ectoparasites:                fleas (e.g. Ctenocephalides spp., such as Ctenocephalides fells and the like);        ticks (e.g. Rhipicephalus spp., Ixodes spp., Dermacentor spp., Amblyoma spp., Haemaphysalis spp., and the like);        mites (e.g. Demodex spp., Sarcoptes spp., Otodectes spp., Cheyletiella spp., and the like);        lice (e.g. Trichodectes spp., Felicola spp., Linognathus spp., and the like);        mosquitoes (Aedes spp., Culex spp., Anopheles spp. and the like); and        flies (Musca spp., Stomoxys spp., Dermatobia spp., and the like).        
Fleas are a problem because not only do they adversely affect the health of the animal or human, but they also cause a great deal of psychological stress. Moreover, fleas may also transmit pathogenic agents to animals and humans, such as tapeworm (Dipylidium caninum).
Similarly, ticks are also harmful to the physical and/or psychological health of the animal or human. However, the most serious problem associated with ticks is that they are vectors of pathogenic agents affecting both humans and animals. Major diseases which may be transmitted by ticks include borreliosis (Lyme disease caused by Borrelia burgdorferi), babesiosis (or piroplasmosis caused by Babesia spp.) and rickettsioses (e.g. Rocky Mountain spotted fever). Ticks also release toxins which cause inflammation or paralysis in the host. Occasionally, these toxins may be fatal to the host.
Animals and humans also suffer from endoparasitic infections caused by parasitic worms categorized as cestodes (tapeworms), nematodes (roundworms) and trematodes (flatworms or flukes). These parasites cause a variety of pathologic conditions in domestic animals including dogs, cats, pigs, sheep, horses, cattle and poultry. Nematode parasites which occur in the gastrointestinal tract of animals and humans include those of the genera Ancylostoma, Necator, Ascaris, Strongyloides, Trichinella, Capillaria, Toxocara, Toxascaris, Trichuris, Enterobius, Haemonchus, Trichostrongylus, Ostertagia, Cooperia, Oesophagostomum, Bunostomum, Strongylus, Cyathostomum, and Parascaris among others, and those that are found in the blood vessels or other tissues and organs include Onchocerca, Dirofilaria, Wuchereria and the extra intestinal stages of Strongyloides, Toxocara and Trichinella. Therapeutic agents are administered to animals by a variety of routes.
These routes include, for example, oral ingestion, topical application or parenteral administration. The particular route selected by the practitioner depends upon factors such as the physicochemical properties of the pharmaceutical or therapeutic agent, the condition of the host and economics. In certain cases, it is convenient and efficient to administer veterinary medicines orally by placing the therapeutic agent in a solid or liquid matrix that is suitable for oral delivery. These methods include chewable drug-delivery formulations. The problem associated with administering oral formulations to animals is that the therapeutic agent often provides an unpleasant taste, aroma, or texture, which causes the animals to reject the composition. This is further exacerbated by compositions that are hard and difficult to swallow.
Oral veterinary compositions in the form of soft chewable compositions (“soft chews”), or chewable tablets that are palatable are usually convenient to administer to certain animals, particularly cats and dogs, and may be used effectively to dose veterinary medicine to these animals. However, many oral compositions comprising active agents with a bitter or unpleasant taste are not well accepted by cats and dogs. Furthermore, when the bioavailability of an active agent from an oral dosage form is not sufficient or is variable, the required exposure of the animal to the active ingredient may not be sufficient to provide the desired efficacy. Problems such as these often lead to low or sub-optimal efficacy and control of parasites.
Chewable dosage forms for drug delivery are well known to pharmaceutical technology. It is known in the pharmaceutical industry that the act of chewing increases the surface area of the available active ingredient and may increase the rate of absorption by the digestive tract. Chewable systems are also advantageous where it is desirable to make an active ingredient available topically to the mouth or throat areas for both local effects and/or systemic absorption. Further, chewable dosage forms are also utilized to ease drug administration in pediatric and geriatric patients. Examples of chewable dosage forms may be found in U.S. Pat. Nos. 6,387,381; 4,284,652; 4,327,076; 4,935,243; 6,270,790; 6,060,078; 4,609,543; and, 5,753,255, all incorporated herein by reference.
Palatability and “mouth feel” are important characteristics to be considered in providing a dosage form, or matrix, for an active pharmaceutical or medicinal. Unfortunately, many pharmaceuticals and other active ingredients have a bitter or otherwise unpalatable taste, or an unacceptable mouth feel, due to the grittiness or chalkiness of the compound, or both. These characteristics make it difficult to incorporate such active ingredients into the current state of the art for chewable dosage forms because the objectionable taste and/or mouth feel make it less likely to obtain compliance by the user. Oral veterinary dosage forms that are not palatable to the animal treated result in low acceptance of the medicament by the animal and a low level of compliance. Thus, there is a need for improved oral veterinary dosage forms that are palatable and well accepted by the treated animal.
Another challenge with oral veterinary compositions, particularly soft chewable compositions, is that the release and dissolution of the active agent from the composition after it is ingested by the animal can be variable and incomplete. This leads to variability in the amount of the drug that is absorbed from the digestive tract of the animal.
U.S. Pat. No. 7,955,632 (incorporated herein by reference) describes palatable, edible soft chewable medication vehicles for the delivery of pharmaceutically acceptable active ingredients to an animal and processes of making the same.
US 2004/0037869 A1 and WO 2004/016252 to Cleverly et al. (incorporated herein by reference) describe non-animal product containing veterinary formulations, including chewable veterinary formulations and tablets, that contain at least one pharmaceutical active agent and do not contain animal products.
US 2004/0151759 A1 and WO 2005/062782 to Cleverly et al. (incorporated herein by reference) describe non-animal product containing veterinary formulations comprising a) at least one nodulisporamide or a nodulisporic acid derivative; or b) a combination comprising i) at least one avermectin or milbemycin derivative; and ii) at least one of praziquantel or pyrantel.
WO 2009/02451A2 and US 2011/0059988 to Heckeroth et al. describe various parasiticidal compositions comprising isoxazoline active agents for the control of parasites on animals. The compositions include compositions for oral administration.
Traditionally, in veterinary formulations, palatability had been achieved by the inclusion of animal byproducts or flavors derived from animal sources into the formulation. For example, it is customary to include excipients, such as chicken powder, liver powder, beef, ham, fish, or rawhide-derived products in dog chews to make the chew attractive and palatable to the dog. See, e.g., U.S. Pat. No. 6,086,940; U.S. Pat. No. 6,093,441; U.S. Pat. No. 6,159,516; U.S. Pat. No. 6,110,521; U.S. Pat. No. 5,827,565; U.S. Pat. No. 6,093,427, all to Axelrod et al. (all incorporated herein by reference).
Notwithstanding the compositions comprising parasiticidal active agents described in the documents above, there is a need for palatable oral veterinary compositions that are well accepted by the animals treated and methods with improved duration of efficacy, bioavailability, and spectrum of coverage to protect animals against endoparasites and/or ectoparasites. Optimal compositions should be palatable and well accepted by the animals, provide good oral bioavailability, be efficacious against external and/or internal parasites, have a quick onset of activity, have a long duration of activity, and be safe to the animal recipients and/or their human owners. This invention addresses this need.